CAD/CAM Follies v_1.0

January 10, 2010bySteven Adler

Jewelers have seen some remarkable advances in CAD software tailored for jewelry over the past few years. In particular are the shortcuts, scripts, and builders found in the Rhinoceros 3D jewelry plug-in programs. These script features shorten programming time and make it much easier for novice designers to deliver new jewelry concepts for manufacturers and retailers. In many cases this new breed of designer/model maker is asked to create a photorealistic rendering that can be shown to management and consumers long before the first sample is produced.
The problem with the foregoing scenario is that a design used for rendering a presentation often falls short of what is needed for manufacturing. In recent years at my company we’ve started calling these oversights “CAD/CAM Follies,” wherein the software allows a CAD designer to do things that simply cannot be manufactured, or, if attempted, produce a substandard product.
The “folly” presented here is part of a series to be shared at the upcoming Santa Fe Symposium in May (for details, visit www. santafesymposium.org).
This example is a simple solitaire to be cast in platinum, in which the crown prongs were to be set with small accent diamonds.

The CAD designer created the ring with center stone prongs that were 1.7 mm by 1.7 mm, proportional to the primary diamond (1 carat/7 mm) and shank (2.5 mm wide at finger rest). He then used a cutter script or builder to create channels with shared prongs for accent diamonds. While this method worked perfectly for a rendering (1), illustrating how the ring will look set with diamonds, it created a nightmare for the platinum caster and bench jeweler. When misused, these cutter scripts and builders can reveal very thin walls that will often fail in casting and/or setting. In this case, the prongs were left with cross sections of 0.051 mm (2), which would not be strong enough to hold the center diamond securely. The entire job needed to be started over again.
The solution to this CAD/CAM folly is simple, although time consuming. Since the CAD designer had not saved prior versions of this ring, we had to design it again, this time offsetting the stones from the surface, leaving only a hint of the culet as a cutter to indicate the setting layout. We also eliminated the channel and shared prong cutter, electing instead to bead set the stones in the crown after casting. The advantage of our revised design was that we maintained the structural integrity of the prongs in casting and provided a better metallurgical condition for setting both the center and accent diamonds.

The lesson in this folly is that business owners and managers would be better served in understanding and communicating a fitness for purpose when relying on CAD/CAM. As we move into the new age of online custom jewelry manufacturing, it will be even more important to design for manufacturability the first time. Ultimately, your reputation and profitability may rely on that ability. This article was also published in the MJSA Journal along with many other technical articles leading up to the Santa Fe Symposium in May.